Reading the Bible Like a Trinitarian: Martin Chemnitz (1591)
Next we must observe this point, that the same designation can sometimes be applied to the essence and sometimes to the person. In accepting this concept there is no diminishing of the distinction. For example, the Son is not the Father, even if the term “Father” is used with reference to the person of the Son. For example, in Is. 9:6 the Son is called the “Father of the world to come” (Vulgate). The name “Father” is used with reference to the essence. And in the sequence for Trinity Sunday the church calls the Holy Spirit the “Father of the poor.” Thus the Son is not the Holy Spirit when the term “spirit” is used with personal reference to Him. But because God is a spirit in essence, the Father is also spirit and the Son is spirit. Thus, these names refer to the essence: “The Father of mercies,” 2 Cor. 1:3: “the Father of spirits,” Heb. 12:9. So also in the Nicene Creed the terms are used in the personal sense, “God of God, Light of light,” etc. And in the Lord’s Prayer the term “Father” can be taken in the essential sense, because He is the antithesis to the creature and the prayer is directed to the entire Trinity. However, the term can also be taken in the personal sense in consideration of the benefits belonging to each of the persons, in accord with the statements of Paul in Rom. 8:15 and Gal. 4:6, “He sent the Spirit of His Son into our hearts crying Abba, Father.” We worship in spirit, John 4:23-24, and we call the first person the Father, because of the Son. And this conforms more closely to the apostolic form of the words.